1. Field of the Invention
The invention relates both to a method for recognizing and for selecting a tone sequence, particularly a piece of music.
2. Description of the Prior Art
Today""s multimedia services permit their users to retrieve pieces of music, video clips and also graphical information from appropriate databases on appropriate request in order to be able to play back and/or store the desired pieces of music or the like. As data transmission speeds become higher and higher and costs of storage space become lower, it will also be possible in future to retrieve films from appropriate suppliers.
By way of example, it is currently possible on the Internet for a user to have music recordings or the like transmitted to him by an appropriate supplier, said recordings then either being stored in a database belonging to the user or being used to produce a CD. Such a request for pieces of music or the like is also possible using mobile radio services, however.
To obtain a particular music recording, the user needs to enter the name or the title of the piece of music and transmit it to the appropriate service provider. The service provider""s database of music recordings is then searched for the requested piece of music in order to transmit it, if it is available in the database, to the user making the request.
In order to be able to supply a desired music recording to a user even when he does not know the title of the piece of music exactly, the search in the service provider""s database also includes the use of associative search algorithms which, despite slight discrepancies between the entered title and the actual name of the piece of music, are able to identify the piece of music or at least offer a selection of several pieces of music having similar titles.
If, however, a user wishes to request a piece of music which he likes very much but whose title he does not know, or at best knows only very vaguely, then it is current virtually impossible for him to request this piece of music.
Against this background, the invention is based on the object of providing methods for recognizing and for selecting a tone sequence, particularly a piece of music, which permit a user to find and select a tone sequence or a piece of music whose title he does not know.
This object is achieved, in terms of recognizing a tone sequence, by the method according to claim 1, and in terms of selecting a tone sequence, by the method according to claim 2. Advantageous refinements and developments of the invention are described in the dependent claims.
Thus, according to the invention, to recognize a tone sequence, the tones in the tone sequence to be recognized are first converted into a note sequence; next, to search for the tone sequence which is to be recognized, its note sequence is compared successively with corresponding note sequences for a multiplicity of tone sequences, and titles are then output for the tone sequence or sequences whose note sequence or sequences matches or match the note sequence for the tone sequence which is to be recognized in a predetermined manner.
The inventive method for selecting a tone sequence uses this recognition method and is distinguished in that a tone sequence which corresponds at least in part to at least a section of the tone sequence which is to be selected is entered, the tones in the entered tone sequence are converted into a note sequence, then, to search for the tone sequence which is to be selected, its note sequence is compared successively with corresponding note sequences for a multiplicity of tone sequences in order to ascertain titles for one or more tone sequences whose note sequence or sequences matches or match the note sequence for the tone sequence which is to be selected in a predetermined manner, and the titles ascertained are output as a list, so that a user can use the title list to select the desired tone sequence.
The basic concept of the present invention is thus that a tone sequence, as presented in audio form to the user and can be reproduced more or less accurately by said user, is first converted into a note sequence, that is to say into a representation as is also used, for example, for writing down pieces of music, and this representation of the desired tone sequence is compared with appropriate note sequences which are associated with individual pieces of music in a database belonging to a service provider, so that it is possible to ascertain the degree of correspondence between the desired tone sequence entered and the pieces of music in order then to output the titles of the tone sequence or sequences which match the desired tone sequence, or the tone sequence which is to be selected, in a predetermined manner.
The invention thus permits a user also to request tone sequences, particularly pieces of music, video clips, and possibly also films using their soundtrack, when only their melody is known to him. The method according to the invention thus permits an intuitive search in databases containing pieces of music or the like, and thus simplifies the use thereof.
In a first refinement of the invention, the tone sequence which has been entered in a user terminal and corresponds to the tone sequence which is to be selected is transmitted to a database station which ascertains the list of titles for one or more tone sequences similar to the tone sequence which is to be selected, and the title list is transmitted to the user terminal for output.
If the user terminal used is a mobile telephone, for example, in order to select a particular piece of music from a service provider using radio channels, then it is advantageous, particularly in terms of good utilization of the transmission link, if the tone sequence which has been entered into a user terminal and corresponds to the tone sequence which is to be selected is converted into a note sequence in the user terminal, the note sequence is transmitted to a database station which ascertains the list of titles for one or more tone sequences similar to the tone sequence which is to be selected, and the title list is transmitted to the user terminal for output.
In order to permit the user also to be able to select a piece of music whose title is not known to him at all, in one particularly advantageous refinement of the invention, a short passage of the tone sequence which is characteristic of the respective tone sequence is transmitted together with each title to the user terminal for output. The user is thus offered not only the title of the respective tone sequence, that is to say the title or titles of the recognized piece of music or possible pieces of music, but rather it is also possible for him to hear a short characteristic passage from the piece of music, for example the main theme or the refrain, so that he can make his selection on the basis of the characteristic tone sequence played back.
It is particularly expedient if, in the method according to the invention, the tone sequence is sung by the user to enter it into the user terminal.
A particularly advantageous refinement of the method according to the invention is distinguished in that, to convert a tone sequence into a note sequence, the pitch frequency fpxe2x80x2 and the tone duration dxe2x80x2 are ascertained for each tone in the tone sequence, and each tone is allocated a musical note on the basis of its pitch frequency fp and a musically quantized note duration d on the basis of a tone duration distribution of the tone sequence.
In this context, it is expedient if, to define the note duration of the tones, the median of the tone duration distribution is first ascertained and the tone duration of the median is equated to the note duration of a xc2xc note, and each tone is allocated an appropriate musically quantized note duration by comparing its tone duration with the ascertained note duration of a xc2xc note.
Thus, according to the invention, the time profile for the pitch frequency is used to ascertain the respective musical tone or the note, that is to say, for example, C, D, E, F, G, A, B and the note duration d. Since, particularly when the desired tone sequence is sung, the note duration d cannot be measured absolutely, the median is ascertained from the tone duration distribution and is equated to the note duration of a xc2xc note. On the basis of this, tone duration intervals can then be stipulated, to which the other customary note durations, that is to say {fraction (1/32)}, {fraction (1/16)}, xe2x85x9, xc2xd and 1, in particular, can then be allocated.
To carry out the comparison to establish a degree of correspondence in a data processing system, it is particularly expedient if each tone sequence is represented by a pitch vector h, which is made up of the individual notes or musical tones, and a tone duration vector d, which is made up of the musically quantized note durations d of the individual tones.
To be able to compare the note sequence for an entered tone sequence with the note sequences in the stored pieces of music successfully even when the entered tone sequence has consciously or unconsciously been transposed to another register, in one expedient development of the invention, to establish a correspondence factor Fi,1 between an entered tone sequence and a stored tone sequence, the differences between the pitches h and tone durations d of the respective note sequences are compared with one another.
One practical refinement of the invention is distinguished in that, when the note sequences for an entered tone sequence and in a stored tone sequence are compared, the note sequence for the entered tone sequence is compared successively with corresponding partial note sequences for the stored tone sequences in order to ascertain a respective correspondence factor f i(x), and in that the correspondence factor Fi,1=fi(x1) which indicates the highest degree of correspondence is allocated to the stored tone sequence as a correspondence factor.
To implement the invention using data processing systems, it is particularly expedient if the correspondence factor ascertained is the lowest value of a function fi(x) which is given by the following equation:             f      i        ⁢          (      x      )        =            α      ⁢                        ∑                      l            =            0                                N            -            1                          ⁢                  xe2x80x83                ⁢                  "LeftBracketingBar"                                    h              ⁢                              (                l                )                                      -                          m              h                        -                          (                                                                    h                    i                                    ⁢                                      (                                          x                      +                      l                                        )                                                  -                                                      m                                          h                      i                                                        ⁢                                      (                    x                    )                                                              )                                "RightBracketingBar"                      +          β      ⁢                        ∑                      l            =            0                                N            -            1                          ⁢                  xe2x80x83                ⁢                  "LeftBracketingBar"                                    d              ⁢                              (                l                )                                      -                          m              d                        -                          (                                                                    d                    i                                    ⁢                                      (                                          x                      +                      l                                        )                                                  -                                                      m                                          d                      i                                                        ⁢                                      (                    x                    )                                                              )                                "RightBracketingBar"                    
where xcex1 and xcex2 are weight factors for which: 0 less than xcex1, xcex2 and xcex1+xcex2=1; h(l) is the pitch of the l-th tone in an entered tone sequence, mh is the median of the pitches in the entered tone sequence, d(l) is the tone duration of the l-th tone in an entered tone sequence, md is the median of the tone durations of the entered tone sequence, hi (x) is the pitch of the x-th tone in a stored tone sequence, di (x) is the tone duration of the x-th tone in this stored tone sequence, mhi (x) is the median of the pitches in the interval hi (x) to hi(x+Nxe2x88x92l), mdi (x) is the median of the tone durations in the interval di (x) to di(x+Nxe2x88x921).
To make the selection of the piece of music which is being sought even simpler for the user, in one expedient development of the invention, the tone sequence titles which are to be output are sorted according to a degree of correspondence between the associated stored tone sequences and the entered tone sequence, and the output starts with the title whose tone sequence is most similar to the entered tone sequence, with only titles of tone sequences whose degree of correspondence is higher than a prescribed value being output.
One particularly advantageous refinement of the invention is distinguished in that the note sequences for the multiplicity of tone sequences are stored together with corresponding titles for the tone sequences in a database file, with short characteristic passages of the respective tone sequences being stored together with the note sequences stored in the database file.
Thus, according to the invention, a particular database file is provided in which the note sequences in the pieces of music available in a database are stored together with corresponding names, that is to say with the titles of the pieces of music, so that, when the note sequence for the entered tone sequence is compared, the note sequences in the pieces of music do not need to be produced again every time, which means that the search for the desired piece of music can be significantly simplified and speeded up. In addition to the title of the piece of music, each note sequence may also have a short characteristic passage of the respective piece of music associated with it in this particular database file, for example in MIDI format, which means that the database file in which pieces of music are stored as such does not need to be accessed until the user has decided on a specific piece of music.